In these days, a liquid crystal projector device using a liquid crystal panel as a liquid crystal light valve therein has been developed evidently. As the liquid crystal projector device, there are mainly considered a data projector device configured for a personal computer, a front projector device configured for a home theater, and further, there is considered a rear projector device configured for a rear projection television.
The liquid crystal projector device is roughly divided into two types, that is, a single-panel type which uses a liquid crystal light valve (liquid crystal panel) with color filters of three colors, i.e., R (red), G (green) and B (blue), and a three-panel type which uses three monochrome liquid crystal light valves (liquid crystal panels) for three optical paths of R, G and B, respectively. The liquid crystal projector device is divided into whether a transmission type of projector or a reflection type of projector, depending on whether the liquid crystal light valve which is a center of the liquid crystal projector device is the type of transmission or the type of reflection.
Here, an optical system of a three-panel transmission type of liquid crystal projector device is constructed such that: liquid crystal light valves, each corresponding to each color of R, G and B, are disposed on three light incident planes of a polyhedral dichroic prism (cross prism) in a state of opposing to one another; and R-light, G-light and B-light, each transmitted through the corresponding liquid crystal light valve, are synthesized by means of the dichroic prism and irradiated into a projection lens.
At that time, each liquid crystal light valve generates heat owing to absorption of light or the like. Therefore, the temperature at the time of operation (will be referred to as operation temperature, hereinafter) increases. On the other hand, in the liquid crystal light valve, organic matter is used for not only the liquid crystal itself but also an orientation layer, a seal portion, a polarizing plate, a phase difference plate and the like. In addition, organic matter is also used for a flattening film and the like on a thin film transistor (TFT). Therefore, there has been worry about deterioration of reliability owing to increasing temperature or increasing quantity of light.
For this reason, an air-cooling method using a fan and a liquid-cooling method using liquid have been proposed as a method of cooling the liquid crystal light valve (liquid crystal panel). In the air-cooling method, the liquid crystal light valve is cooled by rotating a fan so as to fan air to the liquid crystal light valve. In the liquid-cooling method, the liquid crystal light valve is cooled by bringing cooling liquid into contact with the liquid crystal light valve.
However, in the air-cooling method, there have been inconveniences such that noises are generated by rotations of the fan or dust rises. In the liquid-cooling method, it is necessary to dispose a liquid-cooling container around the liquid crystal light valve, which disadvantages in regard to miniaturizing. In addition, temperature of cooling liquid is influenced by environmental temperature around the panel. Therefore, cooling effect easily becomes uneven. Furthermore, there is a problem in that sufficient cooling effect is not easily obtained. In particular, as the distance between optical members becomes short owing to miniaturizing, the environmental temperature increases accordingly. Owing to the increase of the temperature, the temperature of the cooling liquid is remarkably increased. Thus, cooling effect is expected to deteriorate.
In the future, with the progress of enhancing high luminance, high quality of images and remarkable minuteness in the liquid crystal projector device, pixel density of the liquid crystal light valve (liquid crystal panel) and density of quantity of light incident into the liquid crystal light valve will be increased. Accordingly, there has been a trend in that the operation temperature of the liquid crystal light valve increases. On the other hand, miniaturization of the liquid crystal light valve (panel size) will be improved. Therefore, it can be expected that increase of the operation temperature will be accelerated. In those cases, the conventional air-cooling method or liquid cooling method cannot restrain the temperature of the liquid crystal light valve from increasing any more, so that it will be further difficult to retain reliability thereof.